UWP - Get ComboBox selected value

MainPage.xaml

<Page
    x:Class="UniversalAppTutorials.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:UniversalAppTutorials"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">
    <StackPanel 
        x:Name="stack_panel1" 
        Orientation="Horizontal"
        Background="Azure"
        Padding="100"
        >
        <ComboBox 
            x:Name="ComboBox1" 
            Header="Select A Color"
            SelectionChanged="ComboBox1_SelectionChanged"
            >
        </ComboBox>
        <TextBlock
            x:Name="TextBlock1"
            FontFamily="Consolas"
            FontSize="25"
            Foreground="Navy"
            Margin="50,5,5,5"
            />
    </StackPanel>
</Page>

MainPage.xaml.cs

using Windows.UI.Xaml.Controls;
using System.Collections.Generic;
using System;


namespace UniversalAppTutorials
{
    public sealed partial class MainPage : Page
    {
        public MainPage()
        {
            this.InitializeComponent();

            // Initialize a new empty Dictionary instance
            Dictionary<String, string> colors = new Dictionary<string, string>();

            // Put some key value pairs into the dictionary
            colors.Add("SILVER", "#C0C0C0");
            colors.Add("RED", "#FF0000");
            colors.Add("GREEN", "#008000");
            colors.Add("AQUA", "#00FFFF");
            colors.Add("PURPLE", "#800080");
            colors.Add("LIME", "#00FF00");

            // Finally, Specify the ComboBox items source
            ComboBox1.ItemsSource = colors;

            // Specify the ComboBox items text and value
            ComboBox1.SelectedValuePath = "Value";
            ComboBox1.DisplayMemberPath = "Key";
        }

        private void ComboBox1_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            // Get the ComboBox instance
            ComboBox comboBox = sender as ComboBox;

            // Get the ComboBox selected item value and display on TextBlock
            TextBlock1.Text = "You selected:\n";
            TextBlock1.Text += "Value : " + comboBox.SelectedValue.ToString();
        }
    }
}